The present invention relates to an improved rotary sliding closure unit and to a liquid melt container, such as a melting crucible, including such rotary sliding closure unit.
It is of course well known to employ sliding closure units on liquid melt containers, such as melting crucibles, to selectively discharge the liquid melt therefrom. Such sliding closure units are normally of the type wherein all of the elements of the unit are located outside of the liquid melt container. There have, however, been proposed various designs of rotary sliding closure units wherein the sliding surfaces, i.e., the sealing surfaces between the stationary refractory plate and the rotary refractory plate, are positioned within the metal jacket of the liquid melt container, i.e., on that side of the metal jacket facing towards the liquid melt within the container. Such proposals are disclosed for example in Austrian Pat. No. 165,292, Austrian Pat. No. 171,189, DE-OS 19 10 247, and DE-OS 20 43 588. The intended advantage, inter alia, of such proposals is to maintain the pouring area and the sliding surface of the closure unit constantly warm by means of the heat of the melt within the container and to thereby avoid solidification of the melt in such area. However, serious disadvantages are inherently attended with such proposals. Thus, the mounting and dismounting of the rotary sliding closure unit is cumbersome and difficult. Additionally, the refractory parts or elements employed in such units are hard to produce and are voluminous. As a practical matter, it has not yet been possible to effectively employ such type of rotary sliding closure unit.